Means for withdrawing a lining of flexible material from the bore of a conduit



T. E. MURRAY.

MEANS FOR WITHDRAWING A- LINING 0F F LEXIBLE MATERIAL FROM THE BORE OF A comoun.

APPLICATION FILED JAN- 6. I921.

Patented Aug. 9-, 1921.

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Specification of Letters latent.

Application filed January 6, 1921. Serial No. 435,407.

To all whom it may concern:

Be it known that I, THOMAS E. MURRAY, a citizen of the United States, residin at Brooklyn, in the county of Kings and tate of New York, have invented a certain new and useful Improvement in Means for Withdrawing a Lining of Flexible Material from the Bore of a Conduit, of which the following is a specification.

ipes or conduits are sometimes made by processes which leave within the bore a lining of paper or flexible fabric, which it is afterward desirable to remove. Such a condition arises, for example, when the conduit is molded from cement or similar plastic material upon a longitudinally removable core-especially when the core :is a wire spiral--inclosed in an envelop or cover of paper which upon the withdrawal of the core, after the cement has hardened, remains in the bore as a lining. This lining not being adherent to the surface of the bore is liable to be detached by a liquid fiow through the conduit, and to be so carried into valves, traps, bendsor smaller branch pipes, where it accumulates and so clogs the passage. My

present invention is a means for withdraw ing said covering of flexible material longitudinally from the conduit.

In the accompanying drawing- Figure 1 is a longitudinal section of a portion of the molded conduit, showing the core, the cover or envelop of flexible material therefor and the inclosing spiral therein. Fig. 2 is a similar view, showing the molded conduit after the withdrawal of the core.

Similar numbers of reference indicate like parts.

Upon the core 1, here shown as a mm or metal strip in spiral form, is applied, preferably by wrapping, a cover 2 of aper or similar flexible sheet material. pon said covering is wound a spiral wire or metal strip 3. Upon'the covered and wound core is applied plastic cement or concrete at to form the conduit body. Preferably before the cement has hardened and while although soft, it is capable of retaining its form if unsupported, I withdraw the core 1. The paper cover now remains in the conduit as a lining, to withdraw which I pull upon one end of the spiral 3, thereby contracting the diameter ofsaid spiral, and also causing it to grip the inclosed cover or lining. By reason of this contraction and engagement, the spiral 3 may be easily withdrawn longitudinally from the conduit, bringing the cover 2 with it, and so leaving the conduit bore entirely free. Because the cement is then soft, the end draft on the spiral 3 causes the turns to more or less obliterate any groove in the inner conduit surface which may remain after the removal of said spiral.

I claim: 1

1. A conduit molding device, comprising a flexible tubular core, and a spiral wire inclosing and engaging said core for withdrawing tHe same longitudinally from the molded conduit.

2. A conduit molding device, com rising a core, a cover of flexible material t ereon, and a spiral wire inclosi'ng and engaging said cover for withdrawing the same longitudinally from the molded conduit.

In testimony whereof I have afllxed mysignature in presence of two witnesses.

THUMAS E. MURRAY. Witnesses: GERTRUDE T. Pon'mn, MAY T. MCGARRY.

Patented Aug. 9, 11921. 

